The present invention relates to compositions of subtherapeutic doses of semduramicin, a polyether antibiotic and coccidiostat in combination with nicarbazin, an anticoccidial agent. These synergistic compositions control and/or prevent coccidiosis in poultry, particularly, strains of coccidia that are resistant to polyethers used alone.
Combinations of polyether antibiotics with nicarbazin are reported to be effective for control of coccidiosis-causing strains of Eimeria in U.S. Pat. No. 4,218,438. From among the combinations claimed in U.S. Pat. No. 4,218,438, the combination of narasin:nicarbazin at doses from 30:30 ppm up to 50:50 ppm was selected for development and is now in commercial use under the trade name Maxiban.RTM.. The synergistic combination of the polyether antibiotic maduramicin and nicarbazin for use against coccidiosis in poultry is reported in EPO 182117. The combination of semduramicin with nicarbazin has not been previously reported.